Nanotechnology is engineering of the very small, at dimensions we have never explored before. The 20th century was transformed by technology that worked on the level of one millionth of a metre, allowing us to study bacteria and metal crystals, and to invent jet engines and silicon microchips.

Nanotechnology works at a scale one thousand times smaller still. It is a new frontier for the 21st century.

"All the rules change," says Mark Miodownik, professor of materials and society at University College London. "Different physical laws dominate, ones we're not used to thinking about at our scale. Gravity is irrelevant and you don't have to worry about joining things together because they'll stick to each other naturally."

This weird behaviour makes nanotechnology a powerful tool and opens up a new, tiny world for exploration.

Activity on the nanoscale already exists and can be split into two broad categories. One of these is nanomaterials, which are substances that are made up of tiny (nanoscale) particles, or larger materials that have tiny (nanoscale) features. They are already found in many different consumer product, from ultra-lightweight, super-strength sporting equipment to anti-microbial coatings.

The second category takes advantage of more complicated uses of nanotechnology. It tries to engineer intricate machines and medicines. These ideas are still largely confined to the laboratory, but some of these more complex applications of nanotechnology are not too far away.

"Biology's machinery is all at the nanoscale, so if you want to start manipulating it, you have to do it there," says Miodownik.

Nanotechnology could allow us to design man-made medicines with the power and precision of nature. Scientists are already using it to grow human tissues and, in a decade's time, we may routinely use lab-grown organs for patient transplants.

Within the next 20 years, combining nanotechnology with devices that print in three dimensions could bring about a revolution in manufacturing. Instead of assembling electronic goods from many separate components, we might instead simply print a number of different products from a single material, or if the product was more complex, use different "cartridges" in the same way that colour printing is different from black and white. Looking even further into the future self-healing materials may one day be used in surgical implants, while advances in "quantum" computers could pave the way for artificial intelligence.

Because nanotechnology is so novel and so powerful, many people worry about its unknown risks and potential dangers.

"The risk most talked about is the ability of nanotech carbon tubes to potentially cause asbestosis-type illnesses," says Mike Childs, a spokesperson for Friends of the Earth. "There are concerns that the long-term effects of nanomaterials in the environment and in the human body have not been studied enough yet, and that perhaps we should be more cautious about adding them to consumer products."

Then there is the effect on the environment. Nanotechnology could both improve and worsen environmental problems.

"At the moment, the manufacture of nanoparticles is very energy intensive," says Childs. "But nanotech could make solar panels more efficient and could be vital in making step-changes in energy storage technologies."

Then there are concerns that sound more like a science-fiction film. Larry Millstein, president of the Foresight Institute, says: "Self-replication has given rise to many interesting and imaginative scenarios, some of which are alarming." These scenarios include a swarm of all-consuming, self-replicating nanorobots. However, Millstein emphasises that these machines do not currently exist and that the fear is not of nanotechnology itself, but of its potential to enable the construction of such "nanobots".

Today, nanotechnology is monitored and regulated by the same procedures as other products and medicines. "I don't think we necessarily need more regulatory bodies," says Childs. "But those that already exist have to be open about their state of knowledge and the decisions they are making." Much of nanotechnology is developed by industry, so a key issue is how best to engage with the public, whom Childs believes are largely in the dark.

"There is no obvious cover-up, but neither are there significant efforts to inform and involve the public," Miodownik says. "Scientists need to be seen to be having public discussions. It's the public who need to give permission for certain things to happen and not just be informed later."

Perhaps the internet could provide a solution, suggests Miodownik. "Scientists are really good at using the internet, so let's publish all the data. Let's build huge websites and let's be really open."

Nanotech in everyday life

Nanotechnology sounds like a futuristic concept and some of its more eye-catching applications remain more science fiction than science fact. But it is already making a difference in a lot of ways.

It is used widely in medicine to help deliver drugs to the right place in the body, so making them more effective and reducing the chances of harmful side-effects. It also helps to diagnose conditions, such as heart disease, without the need to operate.

Most people use nanotechnology in their homes, in easy-to-clean surfaces on ceramics or glasses, or in anti-microbe coatings on chopping boards. Even in their food and drink – tiny additives made with nanotechnology have been used to introduce flavours and enhance the taste of cooking oil and chocolate drinks.

There are nano-fibres in clothes, to make shirts wrinkle free and trousers stain-repellent, and even odour-eating socks made with nanotechnology.It is often found at the cutting edge of sport, too – from tennis rackets to golf clubs, athletic equipment increasingly relies on nanoparticles to be strong and light.

New sunscreen creams use nanotechnology to make them transparent, yet still able to block harmful rays, and sunglasses frequently come with a scratch-resistant coating – another use of nanotechnology.

Then there are anti-microbial bandages, used to keep wounds clean, and numerous uses of nanotechnology in the information and computer industries. Liquid crystal displays and microprocessors exploit the technology, while new batteries and electronic components that use nanotechnology are being introduced.